What are the possible symptoms and signs of elevated homocysteine levels?

Elevated homocysteine levels in the body do not cause any symptoms.

Elevated homocysteine levels affect the interior lining of blood vessels in the body, increasing the
risk of atherosclerosis or narrowing of blood vessels. This can result in early
heart attack and stroke.

There is a relationship between the levels of homocysteine in the body and
the size of the carotid arteries that supply the brain with blood; the higher
homocysteine level, the narrower or more stenosed the carotid artery.

In infants who have the genetic condition homocystinuria, the inherited
abnormalities affect the body's metabolism of homocysteine to cysteine. This may
result in dislocation of the lens in the eye, sunken chest, Marfan-type appearance (long thin body type), mental retardation, and
seizures.
Neonatal strokes may also be seen with high homocysteine levels.

In pregnancy, homocysteine levels tend to
decrease. Elevated homocysteine levels may be associated with some fetal
abnormalities and with potential blood vessel problems in the placenta,
causing abruption. There may also be an association with
pre-eclampsia.